*Grin* my husband asked me to promise, in writing, that I wasn't going to buy more lighting for the tank six weeks in. Of course I didn't - I reserve the right to save up for MH if I ever decide to do an SPS reef

Seriously though, I have considered other costs and still want to go ahead.
No flaming, but we're not getting an RO unit - at least not for a while. Our tap water is great - 0-2ppm NO3, undetectable PO4, 30ppm Ca; basically there's not much in it. I've been using tap on my reef for ages now and everything looks happy, but by all means if at any point we need to get an RO/DI we will. There's also a grocery store across the street that has distilled water in 5g jugs in case of emergency.
Drilling the tank isn't an option, there's no room for a sump. The tank is in a book nook with 8" of clearance on either side, and the way the stand is shaped, it's two shelves on either side with a little cabinet <12" wide in the middle. There's just enough room for the canister, but that's it. I still have the Prizm skimmer which will have to do for now, basically I want to go low-tech FOWLR and not overload the tank. My husband loves the gorgeous colours of marines, but there are lots that aren't nano or reef friendly. This will be an opportunity to keep one or two slightly larger fish (with a few smaller ones) that may be coral nippers and experience those colours!
I've got a Potter's angel on order at work, they're one of the most gorgeous fish I've ever seen. They come in teeny, so if it's ready to go before the 65g is ready in two or three (or four or six) months, it can stay in the tank at work (in QT) and/or live in the 30g for a bit. I'll probably end up moving the crazy maroon into the 65g as well and leave the three musketeers in the 30g (Lubbock's fairy wrasse, o-s shrimp goby and yellow clown goby).
I love the idea of an auto top-off, but if it goes anywhere it would be on the 30g - that tank evaporates 1.5L a day! I have a 1L bottle with some small-diameter airline and an IV unit thumb-wheel set up to drip water slowly into the tank all day long. It's my own little ghetto auto top-off, lol. The 65g doesn't evaporate much, I'm not sure if it's because it's well covered (which could be a problem when I go salty) or because of its location, or just the water volume doesn't show it as much, but it's not a problem - right now, I top it off once between water changes if at all.
I bought a cooler today to transport my fish to the store and bring the rock home, I'm all set. Tomorrow is 'double points day' at Big Al's, so if I can get everything together I'll go in the afternoon and make the big swaperoonie. The only frustrating thing is that there's no way I can mix up 60+ gallons of SW ahead of time, so I'll need to do it in the tank. I've got 10g mixing right now, but it means the LR will be sitting in a Rubbermaid bin for at least half a day while the water in the tank circulates and 'ages' a bit. I hope it's at least partially cured, or that bin full of rock is going to get really nasty, really quickly.